2011 NOBEL PRIZE IN PHYSICS October 4, 2011

The Royal Swedish Academy of Sciences said American Saul Perlmutter would share the 10 million kronor ($1.5 million) award with U.S.-Australian Brian Schmidt and U.S. scientist Adam Riess. Working in two separate research teams during the 1990s – Perlmutter in one and Schmidt and Riess in the other – the scientists raced to map the change in the universe’s expansion over time. They were measuring the change in Hubble’s Constant, by analyzing a particular type of supernovas, Type Ia, or exploding stars.

SN 1994D in NGC 4526. in lower left

Type Ia supernovas are thought to be caused by a white dwarf star exceeding its maximum mass, the Chandrasekar limit, of about 1.4 Solar masses, collapsing and detonating into a supernova. Since this collapse occurs at the same mass limit , it’s though all Type Ia supernova are equally bright.

They found that the light emitted by more than 50 distant Ia supernovas was weaker than expected, a sign that the universe was expanding at an accelerating rate, the academy said.

“For almost a century the universe has been known to be expanding as a consequence of the Big Bang about 14 billion years ago,” the citation said. “However the discovery that this expansion is accelerating is astounding. If the expansion will continue to speed up the universe will end in ice.”

Perlmutter, 52, heads the Supernova Cosmology Project at the Lawrence Berkeley National Laboratory and University of California, Berkeley.

Schmidt, 44, is the head of the High-z Supernova Search Team at the Australian National University in Weston Creek, Australia.

Riess, 41, is an astronomy professor at Johns Hopkins University and Space Telescope Science Institute in Baltimore, Maryland.

Schmidt said he was just sitting down to have dinner with his family in Canberra, Australia, when the phone call came.

“I was somewhat suspicious when the Swedish voice came on,” Schmidt told The Associated Press. “My knees sort of went weak and I had to walk around and sort my senses out.”

The academy said the three researchers were stunned by their own discoveries – they had expected to find that the expansion of the universe was slowing down. But both teams reached the opposite conclusion: faraway galaxies were racing away from each other at an ever-increasing speed.

The discovery was “the biggest shakeup in physics, in my opinion, in the last 30 years,” said Phillip Schewe, a physicist and spokesman at the Joint Quantum Institute, which is operated by the University of Maryland and the federal government.